Deep submergence heating system

ABSTRACT

An underwater heating system for a swimmer or diver operating at deep submergence in cold water for extended periods of time. Heat is provided to the swimmer by an exothermic chemical reaction of phosphorous trichloride and water reacting within a continuous heating tube located underneath a swimer&#39;&#39;s diving suit or within an underwater chamber. The heat provided is controlled by regulating the amount of chemicals reacting and safety valves are provided to stop the reaction at any time.

United States Patent INVENTOR.

' DAN/EL L. CURTIS WMQM ATTORNEY Recent programs sponsored by private research organiza- 5 tions and the Government illustrate the need for a self-contained lightweight heating system for swimmers to wear when they are deeply submerged in extremely cold water for prolonged durations.

Conventional foam neoprene wet suits, which are suits that use a stagnant water layer between the suit and the skin of the wearer for protection, will provide adequate insulation where the watertemperature is 50 F. or above and the swimmer is not operating at very great depths. The typical foam wet suit is unsatisfactory when more severe conditions are encountered. Even at shallow depths, when the water temperature approaches freezing, swimmers are restricted by the numbing effect of the water to less than an hours working time. Where submerging for longer durations is required, supplemental heat must be supplied to the diver.

The system described in my Copending application Ser. No. 825,814 filed May 19, 1969, entitled Underwater Heating Systemf and assigned to the assignee of the instant application, describes a heating system which is self-contained and meets the heating requirements of a swimmer operating at relatively shallow depths. However, because of the limitations on that system imposed by the characteristics of ammonia to remain in a liquid state beyond a depthof approximately 130 feet in water of 29 F., such a system becomes unusable at greater depths.

The only other effective underwater portable heating system for use at great depths was developed by the United States Navy and the Atomic Energy Commission for use in the deep submergence undersea research project known as Sealab lll. That system utilized a radio isotope used in conjunction with a liquid cooling garment and a battery operated liquid pump. The cost and complexity of this unit makes it impractical for general purpose use and the cost is prohibitive. Additionally, because of the heat losses due to the complex plumbing'and heat exchanger thermal losses to the ocean, the system has to generate 30 percent more heat than reaches the wearer.

Otherjpreviously known chemical systems have mixed the chemicals to be reacted at the inlet of a heating garment with the heated mix then circulated through the garment with a battery powered circulating pump. These systems are unsatisfactory for deep submergence use because all ,the heating takes place at the point where the chemicals mix and the liquid circulated through the garment is uncomfortably hot at some parts at the expense of other parts. Additionally, there is also an excessive amount of thermal loss due to the ocean because the chemical reaction must take place outside of the divers suit. In these suits, failure of the pump or breakage of the plumbing at one of the joints in the heating garment would almost definitely result in severe injury or even death to the swimmer when ever such a failure occurred in deep water at extremely cold temperatures.

It is therefore an object of this invention to provide a selfcontained underwater heating unit to supply a uniform, controllable heat to a swimmer or diver operating at deep submergence for prolonged durations in extremely cold water.

An additional object of the invention is to provide an underwater heating system which will be self-contained, compact and lightweight.

Another object of the invention is to provide an underwater heating system which will maintain constant buoyancy during operation and will have a simple means of heat control.

Another object of the invention is to provide a self-contained underwater heating system that will not involve the use of a separate heat exchanger or circulating pump and will provide higher efficiencies than previously obtainable in conventional systems.

Another object of the invention is to provide a self-contained underwater heating system which is inexpensive to construct and operate, requiring minimal maintenance.

The aforementioned objects of my invention are achieved by heating the swimmer or diver with the heat of solution produced by the exothermic reaction of two chemicals. The chemical reaction takes place along the length of a heating tube located within a divers swimming vsuit or diving ap'- paratus. The chemicals are supplied in a closed loop system to maintain constant buoyancy and valves are provided to control the speed of the chemical reaction and to purge the system where it becomes necessary for safety reasons.

BRIEF DESCRIPTION OF THE DRAWINGS The specific nature of the invention, as well as other objects, aspects, uses and advantages thereof, will clearly appear from the following description and from the accompanying drawings in which:

FIG. l is a schematic representation of a deep submergence heating system in accordance with my invention. i

F IG. 2 schematically illustrates how the heating tube of FIG. l can be located in a heating garment to provide a unifonn distribution of heat to a swimmer.

FIG. 3 is a cross-sectional representation illustrating how the heating tube of my system can be located within the diving suit of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of my invention illustrated in FIG. 1 produces heat in a process based upon the exothermic chemical reaction:

While other chemicals will function in a similar manner to provide comfortable temperatures due to the heat of reaction of the mixed chemicals, phosphorus trichloride is especially adaptable to my invention because it has a high heat of decomposition and the use of water as one of the reactants permits the inclusion of an important safety feature in the system design. Additionally, because its freezing temperature is -132 F. and its boiling temperature is 167 F., it can be easily stored in a liquid state underwater.

In FIG. 1, the water and phosphorus trichloride are each stored in 'Bellofram accumulators 16 and 18 respectively, at a positive pressure which is determined by the springs 17 and 19 respectively. The output of the phosphorus trichloride accumulator 18 is connected through a control valve 21 and a safety valve 24 to the input of a perforated tubing 34 which may be tenned a soaker line. Water is supplied from the accumulator 16 through a check valve 20 or safety valve 25 (open during normal operation) to the input end of heating tube 30. The heating tube 30 has the soaker tube 34 which is of smaller diameter coaxially disposed within it. The soaker tube 34 is perforated with a series of tiny holes and closed at its opposite end thereby uniformly distributing the phosphorus trichloride into the water flowing through the heating tube 30 throughout the length of the tube. The heating tube 34 is arranged to encircle the swimmers body underneath the wet suit, the boundary of which is schematically illustrated as dotted line 33.

As the phosphorus trichloride and water react at the locations of the perforations in the soaker line 34 throughout the heating tube 30, a uniform distribution of heat is produced throughout the tube encircling the swimmers body with hot spots automatically being avoided. The reaction by-products leave the boundary of the covering wet suit 33 through the output end of the heating tube 30 and are collected in the reverse or spring sides of the two accumulators 16 and 18. ln this manner, nothing is lost from the closed heating system and the buoyancy of the swimmer remains constant with time.

The rate of reaction of the chemicals and therefore the amount of the heat generated, can be controlled by dual control valves 20 and 21 in the outlet lines of the accumulator tanks 16 and 18 respectively. These controls also provide adjustment to maintain a correct ratio of mixture of the two chemicals in the heating tube independent of heat output.

tively. These valves can be connected to a single toggle switch sov that in an emergency, throwing the toggle switch will open valve 24 thereby stopping the flow of phosphorus trichloride to reaction areas of the system and close valve 25 thereby purging the system with water. This action, should it ever be required, will simultaneously stop heating and purge the lines with nontoxic water. As an additional safety feature a pressure relief valve 35 is provided at the output of the heating tube 30 to obviate the possibility of a pressure buildup in the system. The pressure relief valve -35 can be set to open at a predetermined pressure. i

In the system described, the heat of reaction of phosphorus trichloride is 65,000 calories per mole which converts to about 880 BTUs per pound for each pound of phosphorus` trichloride acting with 0.4 pounds of water. A 35,000 BTU system which is considered sufficient to heat a swimmer at a depth of 200 feet in 29 F. water will therefore require 40 pounds of phosphorus trichloride and 16 pounds of water. This represents a total storage volume of two-thirds of a cubic foot which is considered to be rather bulky to be carried as a swimmer backpack item and would be very heavy out of the water. v

As an alternative to the swimmer carrying a self-contained system which is sufficient to supply 35,000 BTU-'s or enough chemicals to produce heat for a full -hourmission, an underwater chambei or sledmobile which is provided the swimmer on diving missions can be utilized. A series of disconnect valves and ,l2 are provided in the phosphorus trichloride and water systems so that while the swimmer is in some proximity to the sled, he can switch to supply lines connected to similar Bellofram accumulators attached to the sled. With such an arrangement, the chemical storagevolume associated with the swimmers self-contained gear could be reduced depending upon the free-swimming time needed. Approximately 9 pounds (one-ninth cubic foot) of chemical 'storage is required per hour of free-swimming time, assuming an average heat requirement of 6,000 BTU s per hour. Therefore, even at relatively deep depths, manageable quantities of reactants could. be stored in the self-contained unit sufficient to give the swimmer a reasonable amount of free-swimming time.

ln FIG. 2, a typical arrangement of the continuous heating tube 30 in a swimmers diving suit is illustrated. The tube is arranged in a meandering configuration with the major lengths of the tube being oriented in a vertical direction so that the garment containing the tube may be easily put on and removed by the swimmer. Overlying the heating garment is a conventional wet suit which minimizes system heat loss. The heating tube input 42 and the output 44 are purposely provided outside of the wet suit boundary for safety reasons.

Across section of the heating garment and wet suit is illustrated in FIG. 3. The heating garment is fabricated by sandwiching the heating tube 30 with the soaker line 34 disposed therein between an outer and an inner layer of nylon 50 and 52 respectively. The garment consisting of the nylon layers 52 and 54 with the attached heating tube 30 completely covers the body adjacent the skin 46 with provisions being made for a head shroud and special thermal gloves, such as the Underwater Air Gloves described in my copending application Ser. No. 761,040, filed Sept. 20, i968 and assigned to the assignee of the instant application. The diameter of the heating tubes 30 is approximately one-half inch with its thin wall permitting it to'lieessentially fiat between the nylon layers 50 and 52 and conforming to the body contour. Separation of the tubes as they parallel each other in passing from head to foot is approximately l inch and the exact` separation be determined experimentally by the swimmers inability to differentiate between hot and cold spots. The tube` is continuous from beginning to end to prevent any possibility of joint leakage which might endanger the swimmer.

It is to be understood that the foregoing description is directed to one embodiment of the invention. Various modifications which may be employed include the use of accumulators other than the diaphragm type and variations in the design of the heating tube such as where the heating tube and soaker tube are adjacent rather than coaxially disposed to each other.

I claim. my invention as:

1. An underwater heating system designed for use at great depths comprising:

a. a first chemical source for supply a first liquid chemical;

b. a second chemical source for supplying a second liquid chemical;

c. a heating tube heaving its inlet connected to said first chemical source so that said first chemical can flow therethrough;

d. chemical mixing means disposed throughout the length of said heating tube and having one end connected to said second chemical source to mix said second liquid chemical with said first liquid chemical along the length of said heating tube thereby producing heat throughout said heating tube as a result of an exothermic chemical reaction between said first and second liquid chemicals; and

e. a contained waste receiving means to receive the mixture of said first and second liquid chemicals at the output of said heating tube so that the buoyancy of the system remains constant with time.

2. The system of claim 1 wherein said chemical mixing means includes a mixing tube of smaller diameter than said heating tube, perforated by a series of distributed holes and located within said heating tube.

3. The system of claim l further including a pressure relief valve connected to the output of said heating tube which will open to ambient water if the pressure exceeds a predetermined limit.

4. The system of claim 3 wherein said first and second chemical sources are diaphragm type accumulators, the output of said heating tube being connected to divide the mixed chemicals flowing therefrom into the reverse sides of said accumulators.

5. The system of claim 4 further including first and second safety valves connected to the output of said heating tube and chemical mixing means respectively which when activated will cut off flow of said second chemical into the mixing means and flush the heating tube with said first chemical.

6. Thesystem of claim 5 wherein said first chemical is water.

phosphorus trichloride. 

1. An underwater heating system designed for use at great depths comprising: a. a first chemical source for supply a first liquid chemical; b. a second chemical source for supplying a second liquid chemical; c. a heating tube heaving its inlet connected to said first chemical source so that said first chemical can flow therethrough; d. chemical mixing means disposed throughout the length of said heating tube and having one end connected to said second chemical source to mix said second liquid chemical with said first liquid chemical along the length of said heating tube thereby producing heat throughout said heating tube as a result of an exothermic chemical reaction between said first and second liquid chemicals; and e. a contained waste receiving means to receive the mixture of said first and second liquid chemicals at the output of said heating tube so that the buoyancy of the system remains constant with time.
 2. The system of claim 1 wherein said chemical mixing means includes a mixing tube of smaller diameter than said heating tube, perforated by a series of distributed holes and located within said heating tube.
 3. The system of claim 1 further including a pressure relief valve connected to the output of said heating tube which will open to ambient water if the pressure exceeds a predetermined limit.
 4. The system of claim 3 wherein said first and second chemical sources are diaphragm type accumulators, the output of said heating tube being connected to divide the mixed chemicals flowing therefrom into the reverse sides of said accumulators.
 5. The system of claim 4 further including first and second safety valves connected to the output of said heating tube and chemical mixing means respectively which when activated will cut off flow of said second chemical into the mixing means and flush the heating tube with said first chemical.
 6. The system of claim 5 wherein said first chemical is water.
 7. The system of claim 6 wherein said second chemical is phosphorus trichloride. 